It has often been asserted that psychological factors influence the development of essential hypertension. A review of this literature reveals two consistent findings: (1) that essential hypertensives frequently exhibit negative emotions, and (2) that essential hypertensives exhibit a circulatory pattern typical of a fight-or-flight response when confronted with a psychological stressor. These two findings can be viewed as manifestations of a maladaptive coping strategy, which predisposes essential hypertensives to deal with their environment in a stereotyped manner, e.g., by gating or screening out stimulus input, or by ignoring or classifying all input as irrelevant. This coping strategy is learned and has behavioral and physiological manifestations. These correlates may be present in the potentially hypertensive child, who has adopted this coping strategy, but has not developed increased blood pressure. This possibility is explored in experiments designed to replicate in children the psychophysiological differentiation already demonstrated between essential hypertensive and normotensive adults. Stimulus processing will be assessed both in children of essential hypertensive and normotensive parents and in children whose blood pressure is in the upper quartile for their age. Psychophysiological measurements will include the non-invasive determination of electrodermal response, heart rate, and blood pressure. These experiments are designed to reveal basic stimulus processing differences between potential hypertensives and normotensives which may contribute to their ultimate behavioral and physiological coping strategies.